fix: correctly identify infixed concats as potential SQL injections (#987)

helpers.go

@@ -96,11 +96,46 @@ func GetChar(n ast.Node) (byte, error) {
 	return 0, fmt.Errorf("Unexpected AST node type: %T", n)
 }
 
+// GetStringRecursive will recursively walk down a tree of *ast.BinaryExpr. It will then concat the results, and return.
+// Unlike the other getters, it does _not_ raise an error for unknown ast.Node types. At the base, the recursion will hit a non-BinaryExpr type,
+// either BasicLit or other, so it's not an error case. It will only error if `strconv.Unquote` errors. This matters, because there's
+// currently functionality that relies on error values being returned by GetString if and when it hits a non-basiclit string node type,
+// hence for cases where recursion is needed, we use this separate function, so that we can still be backwards compatbile.
+//
+// This was added to handle a SQL injection concatenation case where the injected value is infixed between two strings, not at the start or end. See example below
+//
+// Do note that this will omit non-string values. So for example, if you were to use this node:
+// ```go
+// q := "SELECT * FROM foo WHERE name = '" + os.Args[0] + "' AND 1=1" // will result in "SELECT * FROM foo WHERE ” AND 1=1"
+
+func GetStringRecursive(n ast.Node) (string, error) {
+	if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.STRING {
+		return strconv.Unquote(node.Value)
+	}
+
+	if expr, ok := n.(*ast.BinaryExpr); ok {
+		x, err := GetStringRecursive(expr.X)
+		if err != nil {
+			return "", err
+		}
+
+		y, err := GetStringRecursive(expr.Y)
+		if err != nil {
+			return "", err
+		}
+
+		return x + y, nil
+	}
+
+	return "", nil
+}
+
 // GetString will read and return a string value from an ast.BasicLit
 func GetString(n ast.Node) (string, error) {
 	if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.STRING {
 		return strconv.Unquote(node.Value)
 	}
+
 	return "", fmt.Errorf("Unexpected AST node type: %T", n)
 }
 
@@ -201,22 +236,21 @@ func GetCallStringArgsValues(n ast.Node, _ *Context) []string {
 	return values
 }
 
-// GetIdentStringValues return the string values of an Ident if they can be resolved
+func getIdentStringValues(ident *ast.Ident, stringFinder func(ast.Node) (string, error)) []string {
-func GetIdentStringValues(ident *ast.Ident) []string {
 	values := []string{}
 	obj := ident.Obj
 	if obj != nil {
 		switch decl := obj.Decl.(type) {
 		case *ast.ValueSpec:
 			for _, v := range decl.Values {
-				value, err := GetString(v)
+				value, err := stringFinder(v)
 				if err == nil {
 					values = append(values, value)
 				}
 			}
 		case *ast.AssignStmt:
 			for _, v := range decl.Rhs {
-				value, err := GetString(v)
+				value, err := stringFinder(v)
 				if err == nil {
 					values = append(values, value)
 				}
@@ -226,6 +260,18 @@ func GetIdentStringValues(ident *ast.Ident) []string {
 	return values
 }
 
+// getIdentStringRecursive returns the string of values of an Ident if they can be resolved
+// The difference between this and GetIdentStringValues is that it will attempt to resolve the strings recursively,
+// if it is passed a *ast.BinaryExpr. See GetStringRecursive for details
+func GetIdentStringValuesRecursive(ident *ast.Ident) []string {
+	return getIdentStringValues(ident, GetStringRecursive)
+}
+
+// GetIdentStringValues return the string values of an Ident if they can be resolved
+func GetIdentStringValues(ident *ast.Ident) []string {
+	return getIdentStringValues(ident, GetString)
+}
+
 // GetBinaryExprOperands returns all operands of a binary expression by traversing
 // the expression tree
 func GetBinaryExprOperands(be *ast.BinaryExpr) []ast.Node {

rules/sql.go

@@ -98,6 +98,32 @@ func (s *sqlStrConcat) ID() string {
 	return s.MetaData.ID
 }
 
+// findInjectionInBranch walks diwb a set if expressions, and will create new issues if it finds SQL injections
+// This method assumes you've already verified that the branch contains SQL syntax
+func (s *sqlStrConcat) findInjectionInBranch(ctx *gosec.Context, branch []ast.Expr) *ast.BinaryExpr {
+	for _, node := range branch {
+		be, ok := node.(*ast.BinaryExpr)
+		if !ok {
+			continue
+		}
+
+		operands := gosec.GetBinaryExprOperands(be)
+
+		for _, op := range operands {
+			if _, ok := op.(*ast.BasicLit); ok {
+				continue
+			}
+
+			if ident, ok := op.(*ast.Ident); ok && s.checkObject(ident, ctx) {
+				continue
+			}
+
+			return be
+		}
+	}
+	return nil
+}
+
 // see if we can figure out what it is
 func (s *sqlStrConcat) checkObject(n *ast.Ident, c *gosec.Context) bool {
 	if n.Obj != nil {
@@ -140,6 +166,28 @@ func (s *sqlStrConcat) checkQuery(call *ast.CallExpr, ctx *gosec.Context) (*issu
 		}
 	}
 
+	// Handle the case where an injection occurs as an infixed string concatenation, ie "SELECT * FROM foo WHERE name = '" + os.Args[0] + "' AND 1=1"
+	if id, ok := query.(*ast.Ident); ok {
+		var match bool
+		for _, str := range gosec.GetIdentStringValuesRecursive(id) {
+			if s.MatchPatterns(str) {
+				match = true
+				break
+			}
+		}
+
+		if !match {
+			return nil, nil
+		}
+
+		switch decl := id.Obj.Decl.(type) {
+		case *ast.AssignStmt:
+			if injection := s.findInjectionInBranch(ctx, decl.Rhs); injection != nil {
+				return ctx.NewIssue(injection, s.ID(), s.What, s.Severity, s.Confidence), nil
+			}
+		}
+	}
+
 	return nil, nil
 }
 
@@ -157,6 +205,7 @@ func (s *sqlStrConcat) Match(n ast.Node, ctx *gosec.Context) (*issue.Issue, erro
 			return s.checkQuery(sqlQueryCall, ctx)
 		}
 	}
+
 	return nil, nil
 }
 
@@ -165,7 +214,7 @@ func NewSQLStrConcat(id string, _ gosec.Config) (gosec.Rule, []ast.Node) {
 	rule := &sqlStrConcat{
 		sqlStatement: sqlStatement{
 			patterns: []*regexp.Regexp{
-				regexp.MustCompile(`(?i)(SELECT|DELETE|INSERT|UPDATE|INTO|FROM|WHERE) `),
+				regexp.MustCompile("(?i)(SELECT|DELETE|INSERT|UPDATE|INTO|FROM|WHERE)( |\n|\r|\t)"),
 			},
 			MetaData: issue.MetaData{
 				ID:         id,

testutils/source.go

@@ -1712,6 +1712,28 @@ func main() {
 	// SampleCodeG202 - SQL query string building via string concatenation
 	SampleCodeG202 = []CodeSample{
 		{[]string{`
+      // infixed concatenation
+package main
+
+import (
+	"database/sql"
+	"os"
+)
+
+func main(){
+	db, err := sql.Open("sqlite3", ":memory:")
+	if err != nil {
+		panic(err)
+	}
+
+  q := "INSERT INTO foo (name) VALUES ('" + os.Args[0] + "')"
+	rows, err := db.Query(q)
+	if err != nil {
+		panic(err)
+	}
+	defer rows.Close()
+}`}, 1, gosec.NewConfig()},
+		{[]string{`
 package main
 
 import (
@@ -1729,7 +1751,8 @@ func main(){
 		panic(err)
 	}
 	defer rows.Close()
-}`}, 1, gosec.NewConfig()}, {[]string{`
+}`}, 1, gosec.NewConfig()},
+		{[]string{`
 // case insensitive match
 package main
 
@@ -1748,7 +1771,8 @@ func main(){
 		panic(err)
 	}
 	defer rows.Close()
-}`}, 1, gosec.NewConfig()}, {[]string{`
+}`}, 1, gosec.NewConfig()},
+		{[]string{`
 // context match
 package main
 
@@ -1768,7 +1792,8 @@ func main(){
 		panic(err)
 	}
 	defer rows.Close()
-}`}, 1, gosec.NewConfig()}, {[]string{`
+}`}, 1, gosec.NewConfig()},
+		{[]string{`
 // DB transaction check
 package main
 
@@ -1796,7 +1821,8 @@ func main(){
 	if err := tx.Commit(); err != nil {
 		panic(err)
 	}
-}`}, 1, gosec.NewConfig()}, {[]string{`
+}`}, 1, gosec.NewConfig()},
+		{[]string{`
 // multiple string concatenation
 package main
 
@@ -1815,7 +1841,8 @@ func main(){
 		panic(err)
 	}
 	defer rows.Close()
-}`}, 1, gosec.NewConfig()}, {[]string{`
+}`}, 1, gosec.NewConfig()},
+		{[]string{`
 // false positive
 package main
 
@@ -1834,7 +1861,8 @@ func main(){
 		panic(err)
 	}
 	defer rows.Close()
-}`}, 0, gosec.NewConfig()}, {[]string{`
+}`}, 0, gosec.NewConfig()},
+		{[]string{`
 package main
 
 import (
@@ -1856,7 +1884,8 @@ func main(){
 		}
 		defer rows.Close()
 }
-`}, 0, gosec.NewConfig()}, {[]string{`
+`}, 0, gosec.NewConfig()},
+		{[]string{`
 package main
 
 const gender = "M"
@@ -1882,7 +1911,8 @@ func main(){
 		}
 		defer rows.Close()
 }
-`}, 0, gosec.NewConfig()}, {[]string{`
+`}, 0, gosec.NewConfig()},
+		{[]string{`
 // ExecContext match
 package main
 
@@ -1903,7 +1933,8 @@ func main() {
 		panic(err)
 	}
 	fmt.Println(result)
-}`}, 1, gosec.NewConfig()}, {[]string{`
+}`}, 1, gosec.NewConfig()},
+		{[]string{`
 // Exec match
 package main
 
@@ -1923,7 +1954,8 @@ func main() {
 		panic(err)
 	}
 	fmt.Println(result)
-}`}, 1, gosec.NewConfig()}, {[]string{`
+}`}, 1, gosec.NewConfig()},
+		{[]string{`
 package main
 
 import (